ronbros3

my LTX8 was installed back fewyrs, been working good.

FD engine with handset, had it tuned 4yrs ago ,dynoed fine , street manners good.

because of a slight roughness at low speed throttle, cruise, decided to hook up handset too look at tune.

well on screens 17 and 18 all are 00%, manual says only in matrix mode, when plug in handset should be normal mode.

so what is going on here,, runs out fine at full throttle 10.5 on AEM widebd, cruise is around 12.5-14.

except at light throttle at 1650-2000rpm rough runnin, should i add some fuel in the rpmcrs #18 screen?? that now are at 00%

bumpstart

if there is no screen 2-16 ( and only screen 8 ) then the ecu is in normal mode

matrix mode enables the rpm plots other than the single 4000 rpm plot which is screen 8
all maps the same feature replicates the 4000 rpm map for all other rpms,, and you can then custom them

so,, if you have only screen 1, screen 8 then screens 17/18/19 then the ecu is in normal mode
the ecu will use the screen 8 numbers for all load maps,, but use screen 17 or 18 to modify that map at each rpm point when the cruise flag thresholds are up
or when the WOT threshold flags are up
\

this makes a sort of " 2.5D " tune
whilst matrix mode is a 3D tune

if you have nothing in the 17/18 map values then you have a 2D tune,, and you tuner was very lazy at last setup

ideally you should cruise around and observe the vacuum and rpm conditions that relate with cruise in 4th or 5tth gear
,, set that as the cruise threshold,, and then trim ( with lambda ) on map 18 at each appropriate rpm to target a leanish 15 or 16:1 at cruise
( an exhaust temp probe is probs needed to set the cruise tune up leaner if you desire )
ultimately pushing up or down should remove the part throttle stumbles that cant be tuned from the main maps

similarly,, the map 17 ( WOT ) is used to beef up any lean dips in the AFR at each rpm
and you may find the shape of this curve relates with engine port efficiency